Precise engineering of quantum dot array coupling through their barrier widths

Quantum dots (QDs) are analogous to artificial atoms, as they confine electrons with discrete energy levels. They can aggregate to form QD solids whose final properties are based on their cooperative interaction, suitable for many technological applications. Ideal QD solids demand truly monodisperse building blocks to prevent undesirable anomalies. However, so far, the real ones exhibit significant structural variations. Digital structural fidelity is achieved on surfaces through atom-by-atom and molecular manipulation or by self-assembled molecular nanoporous networks. Control of the potential barriers between neighbour QDs is essential to alter the crosstalk (coupling) between the existing units and also to engineer two dimensional electron gases (2DEG). Here^(*), researchers at the CFM, in collaboration with international partners, show that precise engineering of the barrier width can be experimentally achieved by a single atom substitution (sulfur vs. oxygen) in a haloaromatic compound. As a result, the electron confinement is tuned in such a way that it affects the degree of QD intercoupling. This work not only complements the toolbox for tuning surface electronic properties, which started in the 90’s with the quantum corrals, but it is also prone to help in deriving clear conceptual ideas on QD coupling, which is an essential parameter for next-generation computing or device technologies.

Figure. Self-assembly generates perfectly ordered arrays of quantum dots. These confine electrons within them while still allowing crosstalk (coupling), which are tuned through their barrier width.